The integrity of signals travelling through a cable or the traces of a printed circuit board may degrade because of loss and inter-symbol interference, especially at relatively higher frequencies. A redriver may be used to solve this problem. A redriver applies equalization to compensate for channel loss and outputs signals with a high differential voltage. This may allow longer cables to be used and may promote compliance with applicable protocols and cable/connector standards.
A redriver may operate in one or more power saving modes. In these modes (which may be for a long period of time), specifications often require current to be low. This is especially the case for a linear redriver. In order to realize low current, the high speed channel(s) of the redriver may be turned off during signal detection mode.
When a low frequency periodic signal (LFPS) is detected, the high speed channel(s) of the redriver may have only a short window of time (e.g., 40 nS) to be powered-up. However, the power-up time of the high speed channel(s) may be considerably longer (e.g., greater than 100 ns or even a few hundred ns) because of the large size (e.g., heavy parasitic loading) of the channel bias nodes. The inability of the high speed channels to “wake up” in the short period of time required for converged input/output (CIO) mode operation. This may cause performance issues or may otherwise limit operation of the redriver and its host system.